undertrays

[MazdaMatt]

Who is using an undertray?
What is your undertray made of?
Where does it start and end?

In the rules, an undertray is defined as a smooth surface "aft of the front axels". Does that mean that there is no penalty for someone that has a front tray? ie, running from the bumper to the axels?

I've just installed a half-assed tray made of coloplast running from the firewall to the gas tank on the passenger side, and from the firewall to the rear suspenion on the driver's side. (I had to avoid the exhaust, that's why the passenger side is shorter, and there is a gap down the middle).

Anybody else?

[MazdaMatt]

Seriously... 70 views of this thread and NOBODY has an undertray? Are you all just being sneaky so you can covertly take the big grand prize without spilling your top secret setup?

[jonweir]

Most new production cars have underbody treatments to reduce drag. These are very easy to do in plastic and clip to the body, or the designs are putting cables and frame rails on the topside to have a nice flat underbody.

Making an undertray that produces downforce requires a lot of strength and stiffness. It can no longer be clipped plastic. This ends up being a lot more work, and a lot heavier.

I've seen some Japanese aftermarket undertrays in carbon, but those are rare, and probably very expensive.

[MazdaMatt]

Bah, all cars, new and old, under 50k have crap underbody for drag. Even the aero-impressive Prius .Cd can be dropped significantly by adding a smooth underbody. I'm not even going for downforce, just drag reduction as Calabogie is pretty high-speed and my motor has crap power.

So the concensus is that underbody treatment is black art not worth the effort and money? I'll see how my car does at high speeds next month.

[ADAM]

you need a motor to get some high speeds..that weed eater you have is not enough :)

[MazdaMatt]

Not only is it a weed-eater, it is a weed-eater with a "fuel efficient" transmission. I havn't used 4th gear in that car yet!!! Next year if I am still happy with the car, it gets a new powerplant (2.0L, LSD, short gears, clutch/flywheel).

[jonweir]

So the concensus is that underbody treatment is black art not worth the effort and money? I'll see how my car does at high speeds next month.

No, you misunderstood my post.
Reduction in drag is easy, downforce is difficult.
You'll just have to decide if the 1 PIP is worth it for just reduced drag.

[MazdaMatt]

Ah, i see.

Well consider this. The leader of my class has propositioned every event he's attended. That means that if i'm in the class above, I'm STILL competing against the same guy. That means I basically have 5 pips to work with to compete with the same guy. And pips are cheaper than money and my undertray has cost me 20 dollars so far. And my air dam was another 20 and I may have materials for side skirts leftover. My diffuser will be another 20 and my other aero mod will be another 20. If i wanted to add enough power to go up a class, i'd be spending many hundreds.

[ADAM]

I thought your car was handling very nice...it felt crisp and balanced IMO

[MazdaMatt]

Thanks Adam. My car is actually handling very well. I'm not trying to generate downforce, just trying to reduce drag so I can continue to accelerate at higher speeds. My car is aerodynamically retarded by design and aero drag is robbing me of power that could better be used for acceleration.

[ADAM]

he he... I have a easier way...

keep your right foot planted :)

[MazdaMatt]

Not all of us have 8 cylinders attached to that foot. My powerplant is very sought after... by hypermilers.

[Cap'n Pete]

Remove your brakes and all related hardware ;). Probably just excess weight that is slowing you down and completely unnecessary anyways :p.

[MazdaMatt]

You just wish you could brake as late and hard as I can :)